Variable saturable reactor



Nov. 1, 1966 w. GARLOTTE 3,233,279

VARIABLE SATURABLE REACTOR Filed Nov. 19, 1964 Fan 1.

INVENTOR.

United States Patent 3,283,279 VARIABLE SATURABLIE REACTQR Melvin W. Garlotte, Indianapolis, Ind, assignor to Radio Corporation of America, a corporation of Delaware Filed Nov. 19, 1964, Ser. No. 412,534 8 Claims. (Cl. 336-110) This invention relates to electrical components known as saturable reactors, and particularly to a variable saturable reactor.

The saturable reactor of this invention has utility in various circuit applications, but for convenience, will be discussed only in connection with one.

As known, in television receivers a saw-tooth line scanning current is applied to the horizontal windings or coil of the deflection yoke of the picture tube to obtain horizontal scanning of the tube. To provide linear scanning of the picture tube, it is the practice to compensate for the increase in the voltage drop during the scan due to the resistances in the deflection coil and associated circuit elements. One way to accomplish such compensation is to employ a saturable reactor in series with the deflection coil. The saturable reactor is so connected within the circuit that at the beginning of the scan the self-inductance of the saturable reactor, and the voltage drop across the saturable reactor, are at a maximum. During the second half of the scan, when the deflection current changes in direction, the saturable reactor is driven towards saturation and the self-inductance of the saturable reactor and the voltage drop across the saturable reactor are reduced to a minimum. The electrical characteristics of the saturable reactor are such that the increase in voltage drop due to the resistances in the deflection coil and associated circuit elements during the second half of the scan is compensated by the decrease in the voltage drop across the saturable reactor. In this manner, linear deflection is obtained. Due to manufacturing tolerances of the various components of television receivers, it is preferable that the electrical characteristics of the saturable reactors be variable or adjustable to permit matching of each saturable reactor with the electrical characteristics of the television receiver in which it is used.

It is an object of this invention to provide a novel and improved variable saturable reactor.

It is a further object of this invention to provide a variable saturable reactor which is inexpensive and simple to fabricate and to assemble into circuits, which is readily tunable or adjustable, and which is sturdy and not subject to breakage or damage.

For achieving these objects in accordance with one embodiment of this invention, a saturable reactor is provided comprising a wire coil and a non-permanent magnetic core extending through the coil. For magnetizing the core and for obtaining adjustability of the electrical characteristics of the saturable reactor, a permanent magnet is mounted adjacent the core on a reciprocally slidable carriage connected to and driven by a drive screw. A slip clutch mechanism is provided for obtaining reversibility of movement of the carriage and for preventing damage to the elements of the saturable reactor.

Further advantages and features of the invention will be discussed in connection with the drawings wherein:

FIGURE 1 is a plan view of an embodiment of a saturable reactor according to this invention;

FIGURES 2 and 3 are side and end elevations, respectively, of the saturable reactor shown in FIGURE 1;

FIGURE 4 is a section, at an enlarged scale, along line 44 of FIGURE 3; and

FIGURE 5 is a schematic circuit diagram of a horizontal deflection circuit of a television receiver incorporating a variable saturable reactor.

With reference to FIGURES 1-4, a saturable reactor 8 is shown which includes a support member 10 having an L-shape. The short leg 12 of member 10 is provided with a pair of mounting holes 14 by means of which the support member 1% may be mounted on a chassis, not shown. The other elements of the saturable reactor are mounted on the long leg or base 16 of support 10. For supporting such other elements, base 16 comprises a pair of oppositely disposed bifurcated uprights 18, 19 and 20, 21 and a pair of guide walls 22 and 24 (FIGURE 4). The axes 18 and 20 (FIGURE 1) through each pair of uprights 18, 19 and 20, 21 are parallel to one another and parallel to guide walls 22 and 24. Uprights 18, 19 and 20, 21 each have slots 26 (FIGURE 3) leading from the upper ends 27 of the uprights to enlarged circular openings 28.

Mounted between uprights 18, 19 is a tubular coil form 30. The ends 32 of the coil form 30 are received in snap-fit wthin the openings 2% of bifurcated uprights 18, 19. Mounted on the coil form 30 is a wire winding or coil 34 having ends 36. Received within coil form 30 in relatively snug-fit and substantially concentric with coil 34 is a ferrite core 38. Core 38 has the property of being magnetized, but not permanently, when exposed to a magnet field.

Mounted on the pair of uprights 20, 21 is a drive screw 40. Screw 40 comprises a shaft 42 around which is a spiral thread 44 having leading ends 46, 46'. As shown in FIGURE 1, the leading ends 46, 46' of the screw thread 44 taper to an edge. The purpose of this appears hereinafter. The length of the screw thread 44 is equal to the distance between the uprights 20, 21, whereby the leading ends 46, 46 of the screw thread 44 engage the inside walls of uprights 20, 21 and center the screw thread therebetween. One end of shaft 42 extends beyond upright 26) to provide an adjusting knob 48 for the drive screw 40.

Coupled wth the thread 44 of drive screw 40 for movement upon rotaton of the screw is a carriage 50. Carriage 50 comprises a wall 52 having three retaining brackets 54 which define a space in which a permanent magnet 55 may be received. Extending from wall 52 (FIGURE 4) is a generally C-shaped screw-following bracket 56 having an extending lip 61. The screw-following bracket 56 extends inwardly of the thread 44 of screw 40, and is appropriately beveled to provide a smooth meshed engagement with screw 40. Lip 61 overhangs guide wall 24 for guiding the movement of carriage 50 in a direction parallel to wall 24.

As mentioned, a permanent magnet 55 is mounted on carriage 511 within retaining brackets 54. Magnet 55 is of such size as to be receivable within these brackets in snugfit, and to provide slid'able engagement (FIGURE 4) of side 68 of magnet 55 with guide wall 22. Magnet 55 thus cooperates with carriage 51) to confine the carriage-magnet assembly in place on base 16 between guide walls 22 and 24, and to maintain screw-following bracket 56 meshed with screw 40.

No further means are required to secure the described component parts of the variable saturable reactor. Also, the parts lend themselves to easy assembly. In the assembly of the saturable reactor, core 38 is inserted into coil form 30 in concentric relation with coil 34 and is held in place either by friction or by the use of a suitable adhesive. Prior to this, coil 34 has been wound around form 30 in a separate step and in the usual manner. The ends 32 of coil form 30 are then snap-fitted through slots 26 into place within openings 23 in uprights 13, 19. Magnet 50 is placed within retaining brackets 54 of carriage 5t), and the carriage-magnet assembly is fitted into place between guide walls 22 and 24 with lip 61 of bracket 54 overhanging guide Wall 24 (FIGURE 4).

For assembling drive screw 46 onto base 16, carriage 50 is preferably moved to position screw-following bracket 56 immediately adjacent upright 21. The unthreaded end of shaft 42 is then passed through bracket 56 and through the enlarged opening 28 in upright 21. At this point, the leading end 46' of thread 44 is spaced from upright 21 by the thickness of bracket 56. Because thread 44 has a length equal to the distance between uprights 20, 21, the other end 46 of thread 44 extends beyond the inner surface of upright 20. Uprights 20 and 21 are flexible, however, and by applying axial pressure against knob 48 for outwardly flexing the uprights while pressing downwardly against the screw 40, thread 44 may be positioned between uprights 20 and 21 and shafit 42 snap-fitted into place through slot 26 and into opening 28 of upright 20.

In the use of the saturable reactor described, the saturable reactor is connected into an electrical circuit by means of the ends 36 of coil 34.

A known horizontal deflection circuit in which the saturable reactor 8 may be used is shown in FIGURE 5. The horizontal output amplifier tube 72 supplies a line scanning current to the horizontal winding of the deflection yoke 74 via a horizontal output transformer 76.

As known, output transformer 76 provides step-down autotransformer coupling between the output electrode 78 of amplifier tube 72 and the horizontal windings 80 of the deflection yoke 74. One end terminal of yoke 74 is coupled to transformer 76 via tap 79. The other end terminal of yoke 74 is coupled through the coil 34 of saturable reactor 8 to an end terminal 94 of transformer 76. The transformer 76 also provides step-up autotransformer action for delivering fly-back pulses of augmented amplitude to a high voltage rectifier (not shown) coupled to one end terminal 81 of transformer 76. The cathode 84' of a damper diode 86 is coupled to transfomer 76 via tap 88. The anode 90 of damper diode 86 is coupled to the B+ supply of the receiver, and a capacitor 92 is coupled between the plate 90 of damper diode 86 and the end terminal 94 of transformer 76. Th damper diode 86 serves conventional reaction scanning and power recovery purposes, and, in cooperation with capacitor 92, adds to the B+ supply potential to provide a so-called B-boost voltage, as known. A variable inductor 96 is coupled between the end terminal 94 of transformer 76 and a tap 98 on transformer 76 for controlling the width of the horizontal scan.

For controlling the linearity of the horizontal scanning, by compensating for the increase in the voltage drop in the deflection windings 8t} .and autotransformer 76, as explained, the saturable reactor 8 is connected in series between the deflection coil 80 and the end terminal 94 of autotransformer 7 6.

Core 38 of the saturable reactor is not a permanent magnet, and its magnetism is dependent upon the relative positioning of permanent magnet 55 with respect to the core. As known the self-inductance of a coil is a function of the magnetic saturation of the core on which the coil is mounted. The saturable reactor 8 is connected into the circuit shown in FIGURE in such manner that, at the beginning of the scan of the picture tube, the direotion of the current through the coil 34 cancels out or reduces the effect of the field of the permanent magnet 55. The magnetism of the core is accordingly reduced and the self-inductance of the coil, and the voltage drop across it, are then a maximum.

During the second half of the scan, when the current through coil 34 changes in direction, the field of the coil 34 aids the field from the magnet 55 and the core is driven nearer and nearer to saturation. Eventually, the selfinductance and the voltage drop across the coil are reduced to a minimum. By moving magnet 55 relative to core 38, the magnetism of the core can be adjusted so that the increase in the voltage drop during the second half of the scan due to the resistances in the deflection 4 coil and autotransformer during the scan is compensated by the decrease in the voltage drop across coil 34. Linearization of the deflection is thus obtained.

Relative positioning of the magnet 55 with respect to core 38 is achieved by manipulation of knob 48 (FIGURE 1) to effect rotation of drive screw 40, thereby moving carriage 5t and magnet 55 mounted thereon parallel to the axis of the core.

The combination of the flexible uprights 20 and 21, screw thread 44, and screw-following bracket 56 provides a slip clutch mechanism permitting continued rotation of the drive screw in one direction without overtravel of carriage 50 and resulting breakage of the members of the variable reactor. Also, the clutch mechanism provides reversibility of movement of carriage 50 after full travel in one direction. The clutch mechanism works as follows:

As mentioned, thread 44 has a length substantially equal to the distance between uprights 20 and 21. Thus, upon continued rotation of drive screw 40 in one direction, carriage 50 is moved until screw-following bracket 56 eventually engages one of the flexible uprights 20, 21. Continued rotation of drive screw 40 in the same direction presses bracket 56 against the upright and causes outward flexure of the upright until bracket 56 is disposed between the outwardly flexed upright and the end of thread 44. Further rotation of screw 40 causes no further advance of carriage 56 since bracket 56 is now disposed beyond the end of the screw thread. Thus, overtravel of carriage 50 and breakage of the saturable reactor is avoided.

In order to reverse the direction of movement of carriage 50 it is necessary that the screw thread mesh with the side of screw-following bracket 56 pressed against the upright. When drive screw 40 is rotated in the opposite direction, the leading end 46, 46 of the thread 44 begins to screw into the thread in bracket 56. The resiliently flexed upright presses bracket 56 onto the screw thread 44 until the leading end of the thread 46, 46' enters the thread portion on the side of the bracket against the upright, the tapered edge of the leading end 46, 46" of the thread 44 facilitating such entry. Therefore, the screw thread causes advance of the bracket upon continued rotation of screw 4'1).

The flexible uprights 20, 21 thus serve as a resilient stop means for limiting the travel of carriage 5i} and maintaining screw-following bracket 56 in engagement with the thread 44 of drive screw 40 for reversing the direction of travel of the carriage upon reversal of the direction of rotation of screw 40.

What is claimed is:

1. A variable saturable reactor comprising:

a base,

said base having two pairs of support means,

a wire coil having an axis mounted between one pair of said support means,

a magnetizable core extending through said coil,

a drive screw mounted between the other pair of said support means and parallel to said axis, and

a permanent magnet operably connected to said drive screw and being reciprocally moveable parallel to said axis upon rotation of said screw.

2. A variable saturable reactor comprising:

a base,

said base having two pairs of oppositely disposed bifurcated uprights,

a tubular member mounted within one pair of said uprights in snap-fit,

a wire coil mounted on said tubular member,

a magnetizable core snugly received within said tubular member and within said coil,

a drive screw mounted in snap-fit within the other pair of said uprights,

a slideable carriage meshed with said drive screw for reciprocating movement relative to said core upon rotation of said screw, and

a permanent magnet mounted on said carriage for movement therewith.

3. A variable saturable reactor comprising:

a base,

said base having two pairs of oppositely disposed bifurcated uprights,

a tubular member mounted within one pair of said uprights in snap-fit,

a wire coil mounted on said tubular member,

a magnetizable core snugly received within said tubular member and within said coil,

a drive screw mountedin snap-fit within the other of said pair of uprights,

a slideable carriage meshed with said screw for reciprocatlng movement relative to said core upon rotation of said screw,

a magnet mounted on said carriage for movement therewith,

said base having a guide wall,

said magnet being in slideable engagement with said wall for guiding the movement of said carriage and for maintaining said carriage meshed with said drive screw.

4. A variable saturable reactor comprising:

a base,

said base having two pairs of support means,

a tubular member mounted on one pair of said support means,

a wire coil mounted on said tubular member,

a magnetizable core received within said tubular member and within said coil,

a drive screw having a thread mounted on the other of said support means,

a carriage mounted for slideable movement, said carriage having a portion meshed with the thread of said screw,

a magfiiet mounted on said carriage for movement therewit said other of said support means being resilient and acting as stop means for limiting the travel of said carnage,

said stop means being positioned relative to said screw thread for stopping said carriage portion just beyond the ends of said thread and for maintaining said portion in engagement with said thread for reversing the movement of said carriage upon change of direction of rotation of said screw.

5. A variable saturable reactor comprising:

a base,

said base having two pairs of oppositely disposed bifurcated uprights,

a tubular member mounted within one pair of said uprights in snap-fit,

a wire coil mounted on said tubular member,

a magnetizable core snugly received within said tubular memberand within said coil,

a drive screw having a thread mounted in snap-fit within the other of said pair of uprights,

a carriage mounted for slideable movement parallel to said screw,

a bracket extending from said carriage and meshed with the thread of said screw,

a magnet mounted on said carriage for movement therewith,

said other of said pair of uprights being resilient and acting as stop means for limiting the travel of said carnage,

said stop means being positioned relative to said sc-rew thread for stopping said bracket just beyond the ends of said thread and for maintaining said bracket in engagement with said thread for reversing the movement of said carriage upon change of direction of rotation of said screw.

6. A variable saturable reactor comprising:

a base,

two pairs of oppositely disposed bifurcated uprights mounted on said base,

an elongated tubular coil form,

the ends of said coil form being mounted within one of said pairs of uprights in snap-fit,

a wire coil mounted on said coil form,

a magnetizable core snugly received within said form and concentric with said coil,

a drive screw having a shaft and a spiral thread,

said shaft being mounted within the other pair of said uprights in rotatable snap-fit, said shaft extending parallel to said core,

the length of said thread being substantially equal to the distance between said other pair of uprights,

said other pair of uprights being flexible,

a carriage mounted for sliding movement parallel to said screw,

a bracket extending from said carriage and meshed with the thread of said screw for sliding said carriage upon rotation of said screw,

a permanent magnet mounted on said carriage for movement therewith,

said drive screw, flexible uprights, and bracket providing a slip clutch for preventing overtravel of said carriage and for providing reversibility of movement of said carriage.

7. A variable saturable reactor comprising:

abase,

two pairs of oppositely disposed bifurcated uprights mounted on said base,

an elongated tubular coil form,

the ends of said coil form being mounted within one of said pairs of uprights in snap-fit,

a wire coil mounted on said coil form,

a magnetizable core snugly received within said form and concentric with said coil,

a drive screw having a shaft and a spiral thread,

said shaft being mounted within the other pair of said uprights in rotatable snap-fit, said shaft extending parallel to said core,

the length of said thread being substantially equal to the distance between said other pair of uprights,

said other pair of uprights being flexible,

a carriage mounted for sliding movement parallel to said screw,

a bracket extending from said carriage and meshed with the thread of said screw for sliding said carriage upon rotation of said screw,

a permanent magnet mounted on said carriage for movement therewith,

said base having a guide wall extending parallel to said screw,

said magnet being in slideable engagement with said wall for guiding the movement of said carriage and for maintaining said bracket meshed with said thread,

said drive screw, flexible uprights, and bracket providing a slip clutch for preventing overtravel of said carriage and for providing reversibility of movement of said carriage.

8. A variable saturable reactor comprising:

a base,

said base having two pairs of oppositely disposed bifurcated uprights,

a tubular member mounted within one pair of said uprights in snap-fit,

a wire coil mounted on said tubular member,

a magnetizable core snugly received within said tubular member and Within said coil,

a drive screw mounted in snap-fit within the other pair of said uprights, said screw having a thread extending substantially the entire length between said other pair of uprights, the leading ends of said thread tapering to an edge,

said other pair of uprights being flexible,

a carriage mounted for sliding movement,

7 8 a bracket extending from said carriage and meshed ment of said carriage upon the reversal of the direc- With the thread of said screw for sliding said carriage tion of rotation ofsaid screw. upon rotation of said screw, and said carriage being slideable in either direction along References Cited y the Examiner said screw until said bracket is pressed firmly against 5 UNITED STATES PATENTS one of said flexible uprights, whereby said uprights 802 140 8/1959 Mattingly 336 110 X are outwardly flened and said bracket is disposed be- 2,899,654 8/1959 Geiser 336 110 tween said one of said uprights and one end of said thread, thereby preventing overtravel of said oar- LEWIS MYERS Primary Examiner.

riage, and said one upright presses said bracket 10 against said thread to maintain said bracket engaged LARAMIE ASKIN Examiner with said thread for reversing the direction of move- T. J. KOZMA, Assistant Examiner. 

1. A VARIABLE SATURABLE REACTOR COMPRISING: A BASE, SAID BASE HAVING TWO PAIRS OF SUPPORT MEANS, A WIRE COIL HAVING AN AXIS MOUNTED BETWEEN ONE PAIR OF SAID SUPPORT MEANS, A MAGNETIZABLE CORE EXTENDING THROUGH SAID COIL, A DRIVE SCREW MOUNTED BETWEEN THE OTHER PAIR OF SAID SUPPORT MEANS AND PARALLEL TO SAID AXIS, AND A PERMANENT MAGNET OPERABLY CONNECTED TO SAID DRIVE SCREW AND BEING RECIPROCALLY MOVEABLE PARALLEL TO SAID AXIS UPON RELATION OF SAID SCREW. 